Globe valve, this type of valve widely used in the industrial field, drives the valve head through the lifting and lowering of the valve stem, which in turn changes the distance between the valve disc and the valve seat, realizing the opening and closing control of the fluid. It is one of the most commonly used cut-off valves in chemical production, mainly used to control water, steam, compressed air and other pipelines, but for viscosity or easy to crystallize the material is less suitable.
Despite the relatively complex structure of the globe valve, its operation is simple and labor-saving. Globe valves excel in regulating flow and cutting off passageways with slow opening and closing speeds and virtually no water hammer. Its compact structure and distinctive shape features a handwheel and stem at the top of the valve and a threaded and stuffing box sealing section in the center.
When using globe valves, we can judge the opening and closing status of the valve by observing the height of the stem exposed to the bonnet. However, there may be a gap in the portion of the valve where the stem is connected to the bonnet, which can lead to media leakage. However, this problem can be effectively solved by packing seal. It is worth noting that the stem threads of small globe valves are located in the body of the valve, so they are in contact with the medium for a long time and are susceptible to corrosion by the medium.
In order to ensure the service life of the globe valve, the installation needs to pay attention to the direction of the fluid. Engineers recommend keeping the line fluid low in and high out, that is, from the bottom up through the valve seat port. Such an installation helps to reduce the resistance of the fluid in the valve body, reducing the opening and closing force of the valve and ensuring that the valve stem and stuffing box do not come into contact with the medium when the valve is closed, thus reducing the risk of damage and leakage.
In the installation and use of globe valves, you also need to pay attention to the following three points:
Before opening a globe valve, a leakage check should be carried out to ensure that neither the valve nor the stuffing box is free from leakage defects.
If stem operation cannot be done by hand, a special F wrench can be used. However, please note that if the valve cannot be opened even with the F wrench, do not use an extension wrench to force it open or close to avoid damaging the valve or causing a safety accident.
When the globe valve is applied to medium-pressure steam piping, condensate should be removed and the piping should be preheated with steam before opening. The preheating pressure should be maintained between 0.2 and 0.3 MPA to avoid seal damage due to sudden changes in temperature and pressure. After confirming the stable condition, then adjust the pressure to the desired level.
To summarize, globe valves are a powerful assistant in industrial fluid control. Understanding its working principle, installation precautions and usage tips will help you better utilize this tool to ensure the smooth running of the production process.